"Having long been genuine admirers of the United States Postal Service (USPS), which gives amazingly reliable service especially compared with many other countries, our team of investigators decided to test the delivery limits of this immense system. We knew that an item, say, a saucepan, normally would be in a package because of USPS concerns of entanglement in their automated machinery. But what if the item were not wrapped? How patient are postal employees? How honest? How sentimental? In short, how eccentric a behavior on the part of the sender would still result in successful mail delivery?
Testing the Limits:
They sent without packaging, but with postage:
$20 bill in a clear envelope
can of soup
small bag of kitty litter
large wheel of cheese
See the results of what got delivered and what didn't at improbable.com